The present invention relates to a rotary-magnet ratio meter having a pointer shaft which bears a rotary magnet, and wherein the pointer shaft is supported close to the pointer by means of a radial bearing, at another place by means of a further radial bearing, and, at the end opposite the pointer, by means of a thrust bearing.
Such rotary-magnet ratio meters are used for electric indicating instruments in combination with an electrical transmitter, for instance for speedometers, and are generally known.
In the case of rotary-magnet ratio meters it is necessary that the rotary magnet be supported as concentrically as possible with respect to the windings so that the greatest accuracy in measurement results. In one known rotary-magnet ratio meter, the pointer shaft is supported with two radial bearings between rotary magnet and pointer. This has the result that errors in alignment of the radial bearings have a relatively strong effect leading to inaccuracies in the measurement. The fact that the rotary magnet is not supported radially on the side facing away from the pointer, that there is therefore an overhung supporting of the rotary magnet, also contributes to this.